The Science (REM atonia) · 6 min read
What is REM atonia, and why does it keep you still?
During dreaming sleep your brain switches off your muscles on purpose. Sleep paralysis is that switch staying on for a few seconds after you wake.
Every night you cycle through light sleep, deep sleep and REM sleep. REM is where most vivid dreaming happens.
To stop you acting out your dreams, the brainstem releases glycine and GABA. These neurotransmitters block the motor neurons in your spinal cord. Your muscles simply stop receiving the 'move' signal. This is called REM atonia, and it protects you every single night.
Sleep paralysis is a timing glitch, not a malfunction of your body. Your conscious awareness comes back online a few seconds before the atonia is switched off. You are awake, thinking clearly, and still running the protective software of REM sleep.
Two systems are briefly out of sync: awareness (awake) and movement (asleep). That mismatch is the entire event. Breathing continues, the heart continues, and the eyes usually still move.
- Atonia is protective, not pathological.
- You are awake inside a normal sleep mechanism.
- Breathing is automatic and never switched off.
Sources & further reading
Links to peer-reviewed research and recognised medical organisations.
- A clinician's guide to recurrent isolated sleep paralysis
Neuropsychiatric Disease and Treatment, 2016
- Sleep Paralysis
American Academy of Sleep Medicine
- Sleep paralysis
NHS